Lactic acidosis

Onset often subtle with malaise, myalgias, respiratory distress, somnolence and abdominal distress.

Associated with low pH, increased anion gap and elevated blood lactate levels.

Normal blood lactate levels 1-.05 mmol/L.

Stressed patients with critical illness may have a normal lactate level of less than 2 mmol/L.

Lactate is a measure of poor perfusion that results in impaired oxygen metabolism.

The lactate threshold refers to a point during exercise where lactate builds up faster than your it can expelled.



The lactate threshold is recognized by burning or cramping feeling, and is reached  at about 50 to 80% of your VO2 max.

Lactate levels are elevated as a result of severe bacterial infection but do not directly measure the risk for bacterial infection.

Lactate cannot differentiate sepsis from non-sepsis

Hyperlactemia indicates a lactate level of 2-5 mmol/L without metabolic acidosis.

Characterized by persistently increased levels of > 5mmol/L in a association with metabolic acidosis.

May be associated with metformin accumulation and the risk of developing such increases with sepsis, dehydration, excess alcohol, liver insufficiency, renal impairment, infection or surgery.

Fatal in 50% of cases.

Lactate clearance is a calculated change from 2 specimens of blood drawn at different times is a method of assessing tissue oxygen delivery.

Lactate clearance basis presumes shock causing inadequate oxygen deklivery causing mitochondrial hypoxia.

Mitchondrial hypoxia causes oxidatice phosphorylation failure and anaerobic glycolysis pursues with an increase in lactate production.

Anaerobic glycolysis increases cellular lactate which then enters the blood.

Blood lactic acid levels varies with oxygen deficit in tissues.

Abilitry of the body to reduce lactate levels in the blood reflects restoration of oxygen delivery.

Lactic acidosis can occur in the presence or absence of tissue hypoperfusion.

Blood lactate testing is highly sensitive in diagnosing states of tissue hypoperfusion however it has poor specificity.

It is common to have an elevated lactate level for reasons other than tissue hypo perfusion, but it is rare to have a normal lactate level in the presence of tissue hypoperfusion.

An elevated lactate level does not ensure that tissue hypoperfusion

Is present.

To establish the etiology of an elevated lactate level requires clinical information, including history, risk factors, and physical examination.

Type A lactic acidosis is more common then type B and his associated with sepsis, shock and mesenteric ischemia.

Is type A lactic acid doses tissue hypoperfusion results in anaerobic metabolism and lactate production, while in type B lactic acidosis it generally occurs in the absence of tissue hypoperfusion and has several etiologies including malignancy such as leukemia, lymphoma and myeloma, renal, liver disease, drug or toxin intoxication or congenital enzyme deficiencies.

Type B lactic acid doses in malignancy may be due to high cell turnover and a high rate of anaerobic metabolism, even in the presence of adequate oxygenation.

Abnormal insulin-like growth factor and overexpression of hexokinase type II enzyme in malignant cells may increase glycolytic rates and lactate production.

Malignant involvement of liver and kidney can lead to decreased clearance of lactate.

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